Search

BACKGROUND: Muscle weakness is a frequently occurring complication of sepsis, associated with increased morbidity and mortality. Interestingly, obesity attenuates sepsis-induced muscle wasting and weakness. As the adipokine leptin is strongly elevated in obesity and has been shown to affect muscle homeostasis in non-septic conditions, we aimed to investigate whether leptin mediates the protective effect of obesity on sepsis-induced muscle weakness. METHODS: In a mouse model of sepsis, we investigated the effects of genetic leptin inactivation in obese mice (leptin-deficient obese mice vs. diet-induced obese mice) and of leptin supplementation in lean mice (n = 110). We assessed impact on survival, body weight and composition, markers of muscle wasting and weakness, inflammation, and lipid metabolism. In human lean and overweight/obese intensive care unit (ICU) patients, we assessed markers of protein catabolism (n = 1388) and serum leptin (n = 150). RESULTS: Sepsis mortality was highest in leptin-deficient obese mice (53% vs. 23% in diet-induced obese mice and 37% in lean mice, P = 0.03). Irrespective of leptin, after 5 days of sepsis, lean mice lost double the amount of lean body mass than obese mice (P

Additional file 1 : Supplementary Table 1. Genes used.

Figure S3. Ketone body 3-HB does not appear to function as alternative energy substrate during sepsis. The effect of supplementation of glucose (PN+gluc) or 3-hydroxybutyrate (PN+3-HB) to lean (Ln) parenterally fed mice was evaluated after 5 days of sepsis. (a) Relative mRNA of genes involved in muscle and (b) hepatic fatty acid oxidation. (c) Total triglyceride (TG) content of the muscle (as nmol TG per total muscle weight (mg)) and (d) the liver (as μmol TG per total liver weight (mg)). (e) Plasma free fatty acid (FFA), (f) TG, (g) LDL-cholesterol, and (h) HDL-cholesterol concentration. (i) Relative mRNA of genes involved in ketolysis. (j) Plasma glucose concentrations. (k) Total glycogen content of the muscle (as μg glycogen per total muscle weight (mg)). Gene expression data are normalized to Rn18s or Hprt and presented relative to mean of Ln healthy controls (Ctrl). All panels: Ln Ctrl n = 15; Ln Sepsis: PN+gluc n = 17, PN+3-HB n = 17. Data are means ± SEM. p values determined through Wilcoxon or Student’s t test [Wilcoxon p values: (a) Cd36 p = 0.1, Cpt1b p = 0.6, Acadl p = 0.03, Hadha p = 0.3, (b) Ppara p = 0.002, Cd36 p = 0.05, (c) p = 0.001, (d) p = 0.6, (e) p = 0.2, (f) p = 0.004, (g) p = 0.01, (h) p

Figure S4. Effect of 3-HB on markers of autophagy, inflammation and mTOR-related protein synthesis. The effect of supplementation of glucose (PN+gluc) or 3-hydroxybutyrate (PN+3-HB) to lean (Ln) parenterally fed mice was evaluated after 5 days of sepsis. (a) Relative expression of genes and (b) proteins involved in autophagy in the muscle. (c) Relative mRNA expression of genes involved in the inflammatory response in the muscle. (d) Plasma TNF-α concentration. (e) Relative expression of proteins involved in mTOR-related protein synthesis. Gene expression data are normalized to Rn18s or Hprt and presented relative to the mean of Ln healthy controls (Ctrl). Protein expression data are normalized to b-actin and displayed relative to the mean of Ln Ctrl. All panels: Ln Ctrl n = 15; Ln Sepsis: PN+gluc n = 17, PN+3-HB n = 17. Data are means ± SEM. p values determined through Wilcoxon Test [Wilcoxon p values: (a) Atg5 p = 0.01, Atg7 p

Figure S1. Plasma lipid profile and markers of fatty acid oxidation in lean and overweight/obese mice. The plasma lipid profile and gene expression markers of fatty acid oxidation were assessed in lean (Ln) and overweight/obese (Ob) mice after 1 (d1) or 5 days (d5) of sepsis. (a) Plasma free fatty acid (FFA), (b) triglyceride (TG), (c) LDL-cholesterol, and (d) HDL-cholesterol concentrations. (e) Relative mRNA expression of genes involved in fatty acid oxidation in the muscle. (f) Relative mRNA expression of genes involved in hepatic fatty acid oxidation. Gene expression data are normalized to Rn18s or Hprt and shown relative to the mean of Ln healthy controls (Ctrl). For all panels: d1 Ctrl: Ln n = 15, Ob n = 10; d1 Sepsis: Ln n = 15, Ob n = 15; d5 Ctrl: Ln n = 17, Ob n = 15; d5 Sepsis: Ln n = 15, Ob n = 15. Data are mean ± SEM. p values determined through Wilcoxon or Student’s t tests [Wilcoxon p values: (a) d1 p = 0.01, d5 p = 0.6, (b) d1 p = 0.5, d5 p = 0.5, (e) d1 Acadl p = 0.07, d1 Hadha p = 0.2, d5 Hadha p = 0.05, (f) d1 Ppara p = 0.7, d5 Ppara p

Figure S5. Confirmation of adipose tissue-specific ATGL knockout. Markers of adipose tissue-specific ATGL knockout (AAKO) were assessed in overweight/obese (Ob) wild-type (WT) and knockout mice. (a) Relative mRNA expression of Pnpla2/Atgl in visceral (visc.) and subcutaneous (s.c.) adipose tissue (AT), muscle and liver. (b) Summation of visc., s.c., and epididymal AT depot weights after 5 days, as percentage of initial body weight. (c) Plasma glycerol concentration. (d) Ex vivo glycerol release per epididymal AT explant mass. (e) Plasma free fatty acid (FFA) concentration. (f) Relative mRNA expression of genes involved in hepatic fatty acid oxidation. Gene expression data are normalized to Rn18s or Hprt and presented relative to the mean of WT Ob healthy controls (Ctrl). For all panels: Ob Ctrl: WT n = 19, AAKO n = 18; Ob Sepsis: WT n = 19, AAKO n = 17. Data are mean ± SEM. p values determined through Wilcoxon or Student’s t test [Wilcoxon p values: (a) visc. AT p

Figure S2. Plasma insulin. Plasma insulin concentrations after 5 days of sepsis in (a) lean (Ln) and overweight/obese (Ob) mice and (b) in Ln mice receiving either standard mixed parenteral nutrition (PN), or a lipid-rich PN (Lipid). (a) Healthy control (Ctrl): Ln n = 17, Ob n = 15; d5 Sepsis: Ln n = 15, Ob n = 15. (b): Ln Ctrl n = 24; Ln Sepsis: PN n = 23, Lipid n = 23. Data are means ± SEM. p values determined through Wilcoxon or Student’s t test [Wilcoxon p values: (a) p = 0.1, (b) p = 0.01]. § p ≤ 0.05, §§ p ≤ 0.01, §§§ p ≤ 0.001 between Ctrl and Sepsis, * p ≤ 0.05, ** p ≤ 0.01, ***p ≤ 0.001 between sepsis groups. (DOCX 40 kb)

Additional file 1. Additional file 1 contains supplemental Materials and Methods, supplemental table 1 with the list of used probes and primers for gene expression analysis and supplemental table 2 with the list of used antibodies for protein expression analysis.

Table S1. List of commercial TaqManÂŽ assays used for gene analyses. (DOCX 17 kb)

Supplemental Material and Methods. (DOCX 83 kb)

Supplemental Material and Methods. (DOCX 83 kb)

Table S1. List of commercial TaqManÂŽ assays used for gene analyses. (DOCX 17 kb)

Additional file 1. Additional file 1 contains supplemental Materials and Methods, supplemental table 1 with the list of used probes and primers for gene expression analysis and supplemental table 2 with the list of used antibodies for protein expression analysis.